Repairing 305 vs. new Goodwrench 350

[85C1500]

I have an 85 GMC C1500 2 wheel drive with the original 305 engine and TH350trans. The heads on the 305 are cracked so I am either going to replace the heads or replace the entire engine.

I can get a new Goodwrench engine for approx $1700. Will all the parts from my 305, i.e. flywheel, intake mfold, exhaust mfold, starter, crankshaft damper, etc bolt right on to the new 350? I am trying to figure out how much the engine upgrade will really cost.

The other option I have is to replace the 305 heads with rebuilt heads for about $400. The heads are off now and the cylinder bores, camshaft, lifters look OK, however the engine has 100,000 miles on it so I am trying to decide if it makes more sense to just replace the engine w/ the new 350.

Any advice would be much appreciated.

[86swb]

I myself would go with the 350 and I think all parts will fit but not 100% sure.

[GWEE]

i too would swap
i have a 84 with a 305 and going to put a 350 when it brakes.

[swervin ervin]

Yes, everything from the 305 will bolt on the 350.

To be honest with you, I wouldn't repair a 305 if someone fixed it for free. Although I do hear they make good boat anchors.

[Slonaker]

I have done the conversion a year ago. The only thing I can think of that I could not re-use was the flexplate. I had to use one from an '85 (it changed for '86 due to the change of the design of the rear main seal in '86). With an '85, you should be okay there.

The 350 crate engine heads are drilled for 305 and 350 type exhaust manifold, which have a different spacing on one of the bolts for some reason. As long as you go with a crate engine rather than a rebuilt one, you should be fine.

I guess the decision depends on how much you trust the 305 to last. How much life do you need to get from it to make it worth the expense of fixing it? Do you think it will last long enough to make the repair worthwhile? Can you afford the crate engine right now?

BTW, the best price on my crate engine came from summitracing.com after calculating shipping and tax on all of my options. They charged the price of the engine plus 100 shipping.

Slonaker

[85C1500]

I appreciate you guy's input. Very nice pickups you guys have pictured!

Any comments on the reliability and fuel economy of the 305 vs. a 350? I did some research today, and it looks like the 305 is simply an under bored 350. I did see a post on another forum about 305's having head cracking problems.

I took the heads off my 305 because the engine was consuming coolant. When I pressure tested the coolant system, coolant was leaking into a couple combustion chambers. Otherwise the engine ran fine and the 305 has enough power for my use.

I'm not building a hot rod. I'm just trying to maintain this pickup. I haven't decided yet, but based on this pickup's condition (average), It probably makes sense to replace the heads and hope for the best.

Thanks again for your help.

[Jr_Blazer_Boy]

you can pick up a new 350 crate motor for $1400. well worth it

[KMK454]

If you're trying to keep it original then stick with the 305, otherwise a crate 350 will have greater reliability and performance.

[N2TRUX]

If the 305 has 100k on it, then you are wasting any money spent toward it. If you were on a budget and all you could afford was to rebuild the 305 I would still recommend you buy the 350. Not that the 305 is a bad motor, it's just that the extra cubic inches of a 350 are well worth the money spent.

[84 400]

Nothing wrong with a 305 in my mind but the 350 is the route i would go. Alot of people are quick to bash the good eld 305. If you need it on the road then go for the heads. !00k is not that many miles at all. If you can aford the new motor and down time why not?? Or just get a 350 block and build it yourself as time and money permit and slap some nice heads on the 305 that you can transfer over to the 350 later?

Need the truck + fix 305

Disclamer: that is just me though

[82c10]

Originally Posted by 84 400

Nothing wrong with a 305 in my mind but the 350 is the route i would go. Alot of people are quick to bash the good eld 305. If you need it on the road then go for the heads. !00k is not that many miles at all. If you can aford the new motor and down time why not?? Or just get a 350 block and build it yourself as time and money permit and slap some nice heads on the 305 that you can transfer over to the 350 later?

Need the truck + fix 305

Disclamer: that is just me though

there was a guy running 12's on his 305 in a 3rd-gen camaro, and i saw a local guy either run low 12's or high 11's last year

[cliffsta]

I'm gonna go against the grain here...

I say spend the $400 (try and get them for less? LMC sells replacement heads) and drive the 305 till it dies. Don't put out a fire with a flamethrower. If the 305 hasn't been abused, and it ran OK before this issue, it likely still has several good years. If you just need it back on the road ASAP, swap the heads and get 'er going. I don't see the point in spending 4x the money for a new motor when this is "presumably" all that's wrong with it (other than being a 305 )

Heck, if we hadn't been and sprayed the water out of mine BEFORE trying to crank it, my 305 would still be going and its gotta have close to 200,000 EASILY.

Fix what you got, drive it till it actually craps out. Just my .02

[87 STEPPER]

Heres the best crate engine deal out there iv got one of them in my '99 Tahoe and another buddy of mine just put one in his '88 Blazer and both are kick a$$ engines.

Read the entire add and you decide and you dont have to use Ebay if your not a member or dont like that type of thing. the 800 # is there and thats how both of us did it.

PROMAR PRECISION ENGINES<----------Clickie

[BADGMC]

My truck used to be just as yours is. If you're not going to haul a lot of stuff and its just a driver stick with the 305. Make sure to get rebuilt 601 or 416 heads as they a little more efficient. With my old 305 I put a small comp cam in it and an intake and headers and it was plenty of power to smoke the hides rather nicely and it didn't eat gas like most 350s seem to.

[SSC's76]

If the 305 ran good before the head cracked then replace the heads. It's much cheaper and easyer to go that route. If you really want a little more power then go the crate engine route. Your truck being an 85 the "universal" GM crate engine will drop right in and all the 305 components will bolt on just fine, they even send 2 different timing tabs for those upgrading from a 305.

[84slopwaggin]

I'm not sure if you know how much wear is on the bottom end. I've always heard that a engine with that many miles will start to burn oil with new heads installed. You could be wasting time as well as money. If you decide on the new heads for the 305 they won't work well on a 350 if you have to replace the shortblk later. If it's me I bite the bullet and start with a fresh engine. You can find them at your local GM dealer, Summit, Jegs, etc. In my opinion theres nothing wrong with a 305, but when it starts going down hill upgrade to more cubic inches. I feel when GM was going into the economical battles they should have went no smaller than 327ci. I THINK EVERYONE WILL AGREE YOU CAN'T GO WRONG WITH A 350!

[piecesparts]

The torque band width on the GM 350 "Goodwrench" is bigger and better for your daily use. I would make the change, if it were me. I have done a couple of the changeouts and they motors are great for a daily driver.

[augie]

It depends on your budget, if you think the 305 may be not long for this world then it sounds like a good time to step up to the 350. When I did mine everything came over from the 305, I just had to get a new harmonic balancer for the 350.

[woodyjim]

I recently swapped my 305 for a 290HP 350 crate motor in my '84. I have to say I'm pretty pleased with it. I went to the parts counter at a local GM dealership for mine. It's true that Summit and some on-line sites are cheaper, but most want a core returned. I got mine 3 days after I placed the order, no shipping and no core. (They even set it in my truck bed for me). Tax and all around $1900.00. Only thing that didn't seem to be a perfect swap was the damper. It fit fine but the timing mark was in the wrong place. Nothing a TDC guage and a chalk mark won't fix!
Good Luck! Jim

[piecesparts]

Originally Posted by woodyjim

I recently swapped my 305 for a 290HP 350 crate motor in my '84. I have to say I'm pretty pleased with it. I went to the parts counter at a local GM dealership for mine. It's true that Summit and some on-line sites are cheaper, but most want a core returned. I got mine 3 days after I placed the order, no shipping and no core. (They even set it in my truck bed for me). Tax and all around $1900.00. Only thing that didn't seem to be a perfect swap was the damper. It fit fine but the timing mark was in the wrong place. Nothing a TDC guage and a chalk mark won't fix!
Good Luck! Jim

There are two GM dealers within a hundred miles of my house that are GM Perfromance parts outlets. Both of them have the GM crate motors in their warehouses. The last time I needed a motor, I had it in the time it took to drive to their doors. Both dealers have a selection of small blocks to big block 572s ready to go. It is true that the price is a little up compared to what the Summit and Jegs groups list, but put "Truck Freight" shipping (Due to weight and size) and time for delivery, not to mention having a way to lift it out of the freight truck. By the way that means that you the buyer has to be at home when the dang truck arrives (loss of wages at work). I would go for the GM crate and the ease of purchase. Then sell the used 305 to the next guy for a small price to cover your amenities of mounting the new motor.

As for the dampener, there are two ways to handle this: Either put a different pointer on to get the timing at the top of the dampener or get a different dampener. They are not that expensive.

[Slonaker]

Originally Posted by piecesparts

There are two GM dealers within a hundred miles of my house that are GM Perfromance parts outlets. Both of them have the GM crate motors in their warehouses. The last time I needed a motor, I had it in the time it took to drive to their doors. Both dealers have a selection of small blocks to big block 572s ready to go. It is true that the price is a little up compared to what the Summit and Jegs groups list, but put "Truck Freight" shipping (Due to weight and size) and time for delivery, not to mention having a way to lift it out of the freight truck. By the way that means that you the buyer has to be at home when the dang truck arrives (loss of wages at work).

I ordered from Summit. I believe the price was $1349 with truck freight to the terminal. No tax, shipping included. The price has gone up since then, so it might be a couple of hundred more.

I picked it up after work, on my way home. I had it in less than a week. Roadway, I think it was, put it in the back of my pickup with a forklift. I didn't have any of the problems mentioned above, and saved $800-$900. You might do better if you have a cooperative dealer, but it was really hassle-free buying it from Summit.

I wanted to buy it from a local dealer, but the best price they would offer me for the same engine was $2100. I have a friend who works there as a mechanic, who wanted one for his S10, and they quoted him the same price!

If you decide to buy a crate engine, I definitely recommenf that you price it locally and at Summit.

Slonaker

[piecesparts]

Originally Posted by Slonaker

I ordered from Summit. I believe the price was $1349 with truck freight to the terminal. No tax, shipping included. The price has gone up since then, so it might be a couple of hundred more.

I picked it up after work, on my way home. I had it in less than a week. Roadway, I think it was, put it in the back of my pickup with a forklift. I didn't have any of the problems mentioned above, and saved $800-$900. You might do better if you have a cooperative dealer, but it was really hassle-free buying it from Summit.

I wanted to buy it from a local dealer, but the best price they would offer me for the same engine was $2100. I have a friend who works there as a mechanic, who wanted one for his S10, and they quoted him the same price!

If you decide to buy a crate engine, I definitely recommenf that you price it locally and at Summit.

Slonaker

If you happen to live where there are no terminals close, then it gets drop shipped to your home with a off-line carrier and then you have the responsibility of getting it unloaded yourself. That is what it is like around here. The closest terminal is in KC Mo. or Wichita Ks and by the time I drive there, I might as well pick up the GM motor. My last pricing of one was around $1600.00, but that was a little while ago ( a year and a half when Army Dude broke down at my house) so maybe they are that pricey now. I have a machiist friend that wwe go for the idea of bnuilding what I want, if I want anything special.

To me, time is of the essence. IF I am doing this and I need the truck, then it will be done today, not next week.

[Mickey_D]

My old '81 is sitting outside right now in 25 below weather with the block heater and battery charger plugged in. It's got 335,000 miles on the original 305.

And as for hauling ability?

There it is in all its glory with a little shy of 3,500 pounds of cut oak in the back. The engine had absolutely no problem with it for over 10 miles, but the sidewalls of my tires was another story. I could only manage 35-40mph with it and still maintain control.

In the background there you can see my project truck, the '90 Silverado.

And as for the 350 having worse fuel mileage? I think it's the opposite. My truck maintains a steady thirst of about 8-10mpg, whereas my neighbor's identical truck with the 350 in it gets 14-15mpg out of his. And it seems the above example isn't the exception around here, but the norm. Everyone I've talked to has the same experience - the 350 version of the same truck will exceed the 305's mileage by about 10%.

[84slopwaggin]

yep I drove to the dealership(15mins away) paid for the engine, drove around back, they loaded it in the bed, and I was off. I thought about summit or jegs, but I also thought about the problems that Piecesparts brought up. I would do it all over again if I had to.

[MylilBowTie]

I agree some with 87 STEPPER about the fuel consumption issue. A 350 is better able to handle the same load that a 305 might have trouble with. The harder an engine has to work its going to consume more fuel then it would otherwise. Being that the 350 has more torque is doesn't have to strain the engine near as much. Its somewhat a moot point but still a valid point.

One other point that the 305 is getting 8-10 mpg is its worn out so it will use more fuel. Plus with towing loads it is putting more strain on the engine. Not saying the 305 cant handle it just that there are reason for fuel mileage.

I have a 92 305 that is tbi and get 18-19 mpg city driving and it has decent power. So you can get decent mileage from a 305 but there are alot of things to factor in as a whole.

I myself would get a 350 if I had the means to do so. Otherwise I guess you take a gamble with fixing the cylinder heads and seeing how it holds up. I take it the engine over headed and thats the cause of the cracked cylinder heads?